How can I get a REST client (such as the one built into PHPStorm or POSTman) to work with XDebug?
In my current set-up of XDebug, using PHPStorm and the Bookmarklet
https://github.com/tacnoman/dephpugger This lib run the debugger in terminal ( like ipdb for Python and Byebug for Ruby ). Is very easy to use and there is example how to run php cli scripts and webserver.